1. Field of the Invention
The present invention relates to an output device.
2. Description of Related Art
In recent years, a standard called as High-Definition Multimedia Interface (HDMI), which has expanded the Digital Visual Interface (DVI) standard, has been put to practical use (see, for example, Japanese Patent Application Laid-Open Publications Nos. 2007-108198, 2006-108750, and 2005-333472). By the HDMI standard, digital uncompressed image/sound signals can be transmitted, and HDMI signals (image/sound/control signals) can be transmitted through one cable. Consequently, the HDMI standard has advantages that high quality images and sounds do not deteriorate, and that wiring can be simplified.
However, the sound volume of an output device of a television receiver or the like, which can output images and sounds based on HDMI signals, can be operated to be increased or decreased even if no sound signals are included in the input HDMI signals and the output device does not output any sounds. Consequently, the sound volume (especially large sound volume) causing a stress to a user is sometimes set because an operation of increasing or decreasing the sound volume is performed even while no sound signals are input. In this case, if the input of a sound signal is started in the setting as it is, the problem of causing a stress to a user is brought about.
It is an object of the present invention to provide an output device capable of preventing the setting of sound volume causing a stress to a user.